1. Field of the Invention
This invention relates to an electric can-opener incorporating a grinding mechanism adapted to sharpen kitchen knives or knives used in general households.
2. Description of the Prior Art
In an electric can-opener of the type as described, the above-mentioned grinding mechanism comprises a grinding wheel spindle rotated by a motor and a rotatable grinding wheel mounted on the grinding wheel spindle.
A construction for mounting the rotatable grinding wheel on the grinding wheel spindle heretofore known is the following. In this known construction, that is, the grinding wheel spindle is preformed with a flange and external threads, the grinding wheel spindle is inserted into an axial hole of the rotatable grinding wheel, and the grinding wheel is tightened by the flange and a nut screwed on the external threads. In the case of such a construction, mounting of the rotatable grinding wheel on the grinding wheel spindle becomes very rigid. Accordingly, when a knife is urged against the rotatable grinding wheel in order to sharpen said knife, the knife must be carefully urged thereagainst by a suitable force so as to avoid an excessive depression. The reason is that excessive depression causes a stoppage of rotation of the rotatable grinding wheel, resulting in a stoppage of rotation of the grinding wheel spindle so that the motor which drives the grinding wheel spindle becomes burnt, which has to be avoided.
Another reason is that even if the excessive depression noted above does not result in a stoppage of rotation of the grinding wheel, the knife is partly sharpened due to application of such excessive depression thereto so that an uneven sharpness occurs, which has to be avoided.